Technical Field
The present disclosure relates to an organic light emitting display device, and more particularly, to an organic light emitting display device capable of reducing a color-coordinate shift due to changes in temperature by controlling a hole mobility of a hole transporting layer in the organic light emitting display device.
Description of the Related Art
Recently, a light emitting display device excellent in luminous efficiency, brightness, and viewing angle with a high response speed has attracted a lot of attention. A liquid crystal display device has been widely used so far as a display device. However, the liquid crystal display device requires a backlight as a separate light source and has a technical limitation in terms of brightness, contrast, viewing angle, and the like.
Recently, an organic light emitting display device which is self-emitting and thus does not require a separate light source but is relatively excellent in brightness, contrast, viewing angle, and the like has been developed.
Each sub-pixel of the organic light emitting display device includes an organic light emitting diode (OLED), a thin film transistor that drives the OLED, and a capacitor that stores an image signal. In the organic light emitting display device, sub-pixels are disposed in a matrix to display an image.
The sub-pixels of the organic light emitting display device include a red sub-pixel, a green sub-pixel, and a blue sub-pixel capable of displaying three primary colors.
The red sub-pixel includes a red OLED, and is connected to a capacitor and a driving transistor that drives the red OLED. The green sub-pixel includes a green OLED, and is connected to a capacitor and a driving transistor that drives the green OLED. The blue sub-pixel includes a blue OLED, and is connected to a capacitor and a driving transistor that drives the blue OLED.
The red OLED includes a first anode electrode, a hole transporting layer, a red organic emission layer, a cathode electrode, and a capping layer. The green OLED includes a second anode electrode, a hole transporting layer, a green organic emission layer, a cathode layer, and a capping layer. The blue OLED includes a third anode electrode, a hole transporting layer, a blue organic emission layer, a cathode layer, and a capping layer.
The OLEDs are highly vulnerable to oxygen, hydrogen, and moisture. Therefore, the OLEDs are sealed by an encapsulation layer that protects the OLEDs against oxygen, hydrogen, and moisture.